Manufacture of artificial masses from polyvinyl chloride



Patented Apr. 9,

MANUFACTURE OF Art'rmomr. mssns FROM POLYVINYL CHLORIDE Georgwick,Bitterield, Germany, assignor to I. G. FarbenindustrieAktiengesellschaft, Frankforton-the-Main, Germany No Drawing.Application November 6, 1937, Segigs No. 173,121. In Germany November20,

3 Claims. 11. 18--55) The present invention relates to a process forshaping polyvinyl chloride.

It is an improvement of my copending application Serial No. 111,622,filed November 19, 1936. 5 That application describes a process forshaping crude polyvinylchloride in the absence of plastiiligrs bypressing it at a temperature above about According to the presentinvention the process above described can be modified by firstplasticizing the polyvinyl chloride, which may be pulverulent or inpieces, and-rendering it tree from air by thoroughly working it, forexample by kneading, at a temperature above 140 C., for example at about150 to about 160 0., and then moulding the material at a lowertemperature, for example at about 90 to about 110 0., by pressing orspraying. It is surprising that the moulded obiects thus prepared havethe same properties as those which have been pressed or sprayed at ahigher temperature, so that in this manner also it is possible to obtainarticles which are free from strains and have very good mechanicalproperties. The procedure has the advantage that the articles do notlose their original form duringcooling after removal from the mould.

For example 5 kilos of polyvinyl chloride may be plasticized in a heatedmasticator, the heating being so adjusted that the mass attains atemperature of about 160 C; The hot plastic.

mass having this temperature may then be moulded, for instance, in aspray-casting ma-' chine of which the mould is heated at about 105 C. Atthis temperature the moulded articles are mechanically stable and can beremoved from the mould immediately after the moulding operation. Thearticles are free from strains and have goodmechanical properties, forexample a high resistance to breakage and to shock. 40 The polyvinylchloride mentioned in the forefgoing' example has a polymerizationdegree 'K==6 0"(this K value being calculated according to. theequations given in Cellulose-Chemie,

' vol. XIII, 1923, page 60, right column: K=k-10 i 4| It is obvious thatthe invention is not limited to the foregoing example or to the specificdetails giventherein. Thus, ior instance, the temperature to which thepolyvinyl chloride is heated in the first stage, may be varied and asomewhat lower temperature may be used with polyvinyl chlorides oi'alower degree of polymerization. Generally, however, a minimumtemperature of about 140 C, is necessary. 0n the other hand, highertemperatures up to the decomposition point, that is to about 300 0., arepermissible if care is taken that such higher temperatures exertinfluence only for a minimum 01' time. The 10 best kind of heating andthe most suitable temperature to be employed with a particular polyvinylchloride are determined, it necessary, in each case by a simpleexperiment.

Finally, the temperature atwhich mouldin 15 of the material previouslyheated to a/distinct higher temperature, is performed, likewise may bevaried, and as a rule, all temperatures higher than the softening pointof polyvinyl chloride are admissible. Generally, the moulding operation20 may be carried out at a temperature of about C. to about C.

What I claim is: I

1. In the process for manufacturing formed articles of polyvinylchloride tree from softening 25 and plastifying agents the steps whichcomprise heating polyvinyl chloride to a temperature higher than about140 C. while thoroughly working it and moulding the material-underpressure aigoa lower temperature 01' about 90 C. to below 30 2. In theprocess for manufacturing formed articles of polyvinyl chloride freefrom softening and plastifying agents the steps which comprise heatingpolyvinyl chloride to a'temperature of 35 about to about C. whilethoroughly working it and moulding the material under pressure at about90 to about 110 C. I

3. In the process for manuiacturing formed articles of polyvinylchloride free from softening while thoroughly working it and mouldingthe material under pressure at about 105 C.

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